1. Field of the Invention
The present invention relates to wildlife guards for protection of electrical power distribution and substation equipment.
2. Description of the Related Art
Distribution and substation equipment used to supply electrical power have used wildlife protection to prevent wildlife from simultaneously contacting energized and grounded surfaces. If such contact occurred, short circuits and consequent power outages frequently were the result. The wildlife protection was typically applied to an equipment bushing or lightning arrester of the distribution or substation equipment. So far as is known, existing types of wildlife guards have required separate guards for both the bushing and the arrester. For adequate protection, a number of presently available wildlife guards have also required an insulated or covered wire between the bushing and arrester.
Available wildlife guards have posed problems regarding their installation. Some of the present wildlife guard designs have required service interruptions so that the guard could be installed safely by hand on deenergized equipment. These types of wildlife guards were of a unitary, one-piece structure and have required service interruption so that a conductor known in the art as a "stinger," or jumper wire, could be removed from the equipment terminal of an insulator. This removal was needed to enable the conductor to be inserted through the wildlife guard. After the "stinger" wire was reconnected to the equipment terminal, the guard was then fitted to the insulator. It should be noted that this unitary type of wildlife guard could not be used where there was a jumper wire between the equipment insulator bushing and an adjacent lightning arrester. Service interruptions are undesirable to both customers and the electrical utility. A service interruption is a nuisance for customers because it has required customers to reset digital clocks and other such devices. For a utility, a service interruption has required that a fused distribution cutout be opened. On systems with linkbreak cutouts this has required that the fuse link be broken and replaced with a new one. On systems with non-linkbreak, non-loadbreak cutouts, it has been necessary for line crew members to use a load breaking device known in the art as a loadbuster tool to interrupt the load. These devices are cumbersome, time consuming and difficult to use. In addition, the loadbuster tools are expensive to purchase and costly to maintain.
Other available wildlife guards have been a two-piece or hinged design. Although the two-piece guards usually did not require service interruptions, the two-piece or hinged guards have required rubber glove handling in order to avoid direct contact with "hot" current-carrying equipment. Further, where guards were applied near a grounded surface, such as a transformer tank, use of insulating rubber blankets was typically required for the safety of line crew members. There was reluctance to install wildlife guards which called for rubber glove handling of "hot" or live equipment due to practical safety concerns. Line crew members, therefore, typically deenergized equipment before installing contemporary wildlife guards, even those guards having a hinged design or a two-piece design.
For substation applications, a prefabricated guard, the "Squirrel Guard" made by the Raychem Corporation exists, but so far as is known, has been limited to installation on deenergized circuits. This type of guard has been fabricated in two main pieces and has had to be fitted and secured to insulators by hand. It was not shotgun stick installable on energized circuits. In addition, this type of existing wildlife guard has used an insulating cover of either a cone-shaped design, a cylindrical design, a cap-shaped design, or some combination or variation thereof over energized conductors. Such designs have been comparatively large because of their need to fit over and enclose an insulator skirt. Consequently, these cover designs have required significant storage space both in warehouses and on line crew trucks before they were installed.
Further, certain wildlife insulator guards for distribution applications have required custom fabrication of guards into a required shape from sheets of insulative material by end users. In particular, end users have been required to cut these sheets by hand to a required shape adapted to fit the particular distribution equipment. So far as is known, all of these types of wildlife guards are of the two-piece design which require hand-on assembly onto the insulator. This normally requires deenergizing the equipment before installation of the wildlife guard assembly. In addition, distribution cutouts, especially cutout arrester combinations, near grounded equipment have been a major source of wildlife outages. So far as is known, no satisfactory wildlife protection is available for distribution cutouts or for arresters mounted on cutouts as part of an assembly known in the art as a cutout-arrester combination.